EN Safety Standards for Arc Flash

EN 61482-2:2020 / IEC 61482-2:2018
Protective clothing against the thermal hazard of an Electric Arc

This standard specifies PPE Clothing when there is a risk of an Electric Arc – for instance when working with electricity on open equipment or maintenance / switching work. Electric Arc garments come under PPE Regulation Category III. Fabric properties and garment design are important parameters in the certification process of Electric Arc garments.

During a transition period, stock garments can have three different types of marking.

Working with electricity carries a risk of being injured by an Electric Arc. By wearing protective clothing that is tested and certified to withstand the energy of a possible Electric Arc, you help protect yourself against that risk. It is very important to wear protective clothing covering the whole body in order to achieve complete protection. To certify Electric Arc garments according to EN 61482-2, the protective clothing must be tested by at least one of the two different test methods: Open Arc IEC 61482-1-1 and Box test EN 61482-1-2.

Open Arc – IEC 61482-1-1

This test method uses uses an open arc in a medium voltage range (> 1,000V), which is shot towards a fabric sample or a mannequin with protective clothing. Electrodes behind the fabric or garment register the heat transfer through the fabric/garment in order to determine when a person would receive a second degree burn.

In the first stage, the fabric is exposed to different energy levels to obtain an approved Arc Rating. The revised test method is now more strictly controlled and regulated than before, which can mean that previously obtained results may differ from new re-test figures. However, the protection of the clothing is still the same as before, despite the fact that the Arc Rating may sometimes be a lower value after re-testing. In stage two, the protective clothing is tested with the energy level determined by the fabric test result. A new requirement that has been added to the standard in that the tested garment must not have an afterburn time of more than 5 seconds.

In stage two, the protective clothing is being shot with the energy level from the result of the fabric test. All tests result in two different Arc Ratings based on shooting results and the Stoll curve - which is used to calculate the probability that a person will get a burn. The higher the value, the better the protection.

The first result, ELIM (Incident Energy Limit, cal/cm²), lets the user know how much energy the protective clothing can withstand without any risk (or 0% probability) of a second degree burn. The ELIM value is the official value for Electric Arc classification according to the new standard. The second result is either ATPV (Arc Thermal Performance Value, cal/cm²) or EBT (Energy Break Open Threshold, cal/cm²) and lets the user how much energy the protective clothing withstands when there is a 50% probability of a second degree burn. ATPV indicates the energy level required when the temperature of the mannequins skin reaches a level where a second degree burn could occur. EBT indicates the energy level at which the fabric breaks open and can result in a second degree burn.

Since ELIM indicates an energy value at 0% probability of a second degree burn and ATPV/EBT at 50% probability, the ELIM value is usually lower than ATPV/EBT. Large differences between the ELIM and ATPV/EBT results highlight the importance of wearing several layers of garments to ensure you are properly protected.

Box test EN 61482-1-2

The Box test method uses a constrained and direct arc, created by a short circuit in an open cabinet at a low voltage range (400V). The test is performed on fabric and protective clothing in the same way as for Open Arc. The result is divided into two classes: APC 1 (formerly Class 1) – 168kJ (4kA, 400V), APC 2 (formerly Class 2) – 320kJ (7kA, 400V)

Unlike the Open Arc test, there is not a result scale in this garment tests, only two levels where the garment either passes or fails. A garment with one layer of Flame Retardant fabric usually passes APC 1 - even thin shirt fabrics. To pass APC 2, a system with two or three fabric layers or a lined garment is normally required. This makes it more difficult to adapt the protection to the risk, without compromising on comfort. As APC 1 is a relatively low level of protection, we always recommend a basic protection of at least 8 cal/cm2, PPE2 (according to NFPA 70E).

American standard for electrical safety in the workplace - NFPA 70E

This is the American standard for electrical safety in the workplace and is a consensus standard on how to protect workers from the hazards of an Electric Arc. The standard is formed to help employees and workers to understand electrical hazards, help with: risk assessment, arc rated PPE selection and electrical safe working practices. When choosing workwear and other PPE as protection against Electric Arc risks, NFPA 70E states two methods; Incident Energy Analysis or Arc Flash PPE Category method. Which one to use depends on whether the incident energy that a worker may be exposed to has been calculated or not.

SELECTING THE CORRECT PPE

The strength of the protection must be greater than the force of the risk - meaning that the certified protection in cal/cm2 must be greater than the Incident Energy Analysis in cal/cm2.

The table below shows what PPE should be worn and when:

Arc Flash PPE Category method - NFPA 70E:2018 130.7

The Arc Flash PPE Category method is only used when the Incident Energy Analysis has not been calculated. In the Arc Flash PPE Category method, you compare your workplace with those listed in NFPA 70E 130.7 where a recommendation of which PPE category to choose is stated. This method is more insecure and may cause the user to wear unnecessarily thick and heavy clothing, protecting to a level much greater than that which is required.

The Electric Arc protection for clothing is divided into four PPE categories: